KR100901101B1 - Diversity gain with a compact antenna - Google Patents

Abstract

Receiver chain 53 for use in a wireless communication system includes a compact, highly correlated multi-element antenna. Multiple antenna elements 34 and 35 are configured to receive signals from one or more base stations. Highly correlated signal outputs from antenna elements 34 and 35 are optimally synthesized in controller 55 using a set of weighting coefficients. The set of weighting coefficients for each base station signal is determined in response to the spatial signature of the received signal.

Controller, Synthesizer, Demodulator, Remote Station, Base Station

Description

Diversity gain of compact antennas {DIVERSITY GAIN WITH A COMPACT ANTENNA}

background

Field

The present invention relates generally to wireless communication systems and, more particularly, to interference cancellation from signals received in wireless communication systems.

background

Typical wireless communication systems include multiple remote stations and multiple base stations. In general, a communication system is bidirectional, in which a remote station receives signals from a base station as well as a signal from a remote station. To facilitate transmitting and receiving signals on the wireless communication channel, the remote station includes a receiver and a transmitter.

The function of the receiver at the remote station is to maximize the desired amount of received signal while minimizing any amount of unwanted or interfering received signal. In general, the desired signal is radio waves arriving from one sector of a three sector base station in close proximity to the remote station. The desired signal carries information that the remote station will decode and use. Unwanted or interfering signals include signals arriving from the other two sectors of the base station “leaking” into the serving sector. In addition, the unwanted or interfering signal may be from an entirely different base station adjacent to carry carry information intended for use by another remote station in the communication system. The signal received by the remote station and intended for another remote station interferes with the reception of the desired signal by the remote station, making it more difficult to decode the desired signal.

Undesirable effects include "interference" and "fading". Interference refers to any unwanted output that is "grabbed" by the receiver of the remote station. In essence, fading is a kind of magnetic interference due to the multipath nature of the wireless channel. Typically, the desired signal will reach the remote station through many paths because the propagation of the desired signal is “Bouncing” from buildings, cars, trees, etc., adjacent to the remote station. Since multipath signals arrive at a remote station with an arbitrary set of phases, sometimes the signals are in phase, reinforced synthesized, and receive additional output. In other cases, the signals are offset synthesized, the signals are out of phase, tend to be canceled from each other, and a lower output is received. Erasure, in a high scatter environment, can cause the multipath signal output to reduce the intensity for about 1% of the time to 1/100 of its average value. To compensate for the output loss of the multipath signal, the base station needs to send 100 times more output to keep the receiver operating 99% of the time, as if there is no fading.

Therefore, there is a need in the art for an effective method of combining signals at remote stations to maximize the available signals.

summary

Embodiments disclosed herein address the above requirements by synthesizing highly correlated signals at a remote station to maximize the available signal.

The remote station used in the wireless communication system is equipped with a receiver and a compact, highly correlated, multi-element antenna (ANT). The multi-element antenna is configured to receive signals from one or more base stations. The receiver has a search engine configured to receive a signal from each element of the antenna and to determine a spatial signature, including the amplitude and phase of the signal received at each antenna element. The receiver also has a weighting coefficient engine that determines a set of weighting coefficients for each base station signal in response to the spatial signature of the received signal. Using weighting coefficients, a combiner synthesizes a signal received from each of the multiple elements in the antenna to produce an optimally synthesized signal.

Brief description of the drawings

1 is a diagram illustrating a typical modern wireless communication system.

2 is a diagram illustrating a cellular communication system.

3 is a block diagram illustrating a typical handset with two highly correlated antennas.

4 is a graph showing the signal strength received at each antenna of a multi-antenna array.

5 is a block diagram illustrating one embodiment of a highly correlated antenna available to a remote station.

6 is a block diagram of one embodiment of a dual antenna receiver of a remote station.

7 is a block diagram of one embodiment of a controller implemented for use with a dual antenna receiver of a remote station.

details

The wireless communication system can have multiple remote stations and multiple base stations. 1 illustrates one embodiment of a terrestrial wireless communication system having three remote stations 10A, 10B and 10C and two base stations 12. In FIG. 1, three remote stations are found in a mobile telephone device installed in an automobile 10A, a portable computer remote station 10B, and a wireless local loop or meter reading system. The fixed position remote station 10C as shown in FIG. The remote station may be any type of communication device, such as, for example, a pocket personal communication system device, a portable data device such as a personal data assistant (PDA), or a fixed position data device such as a meter reading device. It may be. 1 shows a forward link 14 from a base station 12 to a remote station 10 and a reverse link 16 from a remote station 10 to a base station 12.

Communication between the remote station 10 and the base station 12 may be accomplished using one of a variety of multiple access techniques that, over a wireless channel, eases numerous users in a limited frequency spectrum. Such multiple access techniques include time division multiple access (TDMA), frequency division multiple access (FDMA), code division multiple access (CDMA), and the like. The industry standards for CDMA include the “Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular System”, the TIA / EIA Provisional Standard, named TIA / EIA / IS-95, and its successor standards (herein the set of And IS-95), the contents of which are hereby incorporated by reference in its entirety.

Typically, wireless communication systems transmit signals between a series of base stations and a plurality of remote stations. For example, each base station transmits a signal to remote stations located within a coverage area of the base station, also called a base station cell. Remote stations located within the coverage area of a base station generally communicate with that base station, that is, the preferred base station of the remote station. When the mobile remote station moves from the coverage area of the first base station to the coverage area of the second base station, hand-off occurs. When performing the handoff, the remote station initiates communication with the second base station and sets the second base station as its preferred base station.

2 is a diagram illustrating the coverage area of multiple base stations in a cellular based communication system or network 19. In FIG. 2, there is first a remote station 20 located within the coverage area of the base station 22. Also shown in FIG. 2 are neighboring base stations 24 and 26 and their respective coverage areas. As above, as long as remote station 20 is within the coverage area of its preferred base station 22, remote station 20 maintains communication with that preferred base station. If the remote station 20 is relocated to the coverage area of another base station, such as the adjacent base station 24, the remote station first sets the base station 24 as the base station to perform a handoff process. As the remote station moves through the cellular network 19, it performs this handoff process while moving from coverage area of one base station to another. Although the coverage areas of FIG. 2 are shown as omni-directional, the coverage area may be split into smaller portions using a directional antenna in the same base station.

In a wireless communication system, a communication signal may travel along some other propagation path when propagating between a base station and a remote station. In wireless channels, multipath signals are generated by signal reflections from obstacles in the environment, such as buildings, trees, cars, and people, for example. Multipath signals generated by the characteristics of the wireless channel present problems for communication systems. One characteristic of a wireless channel that suffers from the multipath effect is the time spread introduced into the signal transmitted over the channel. For example, if an ideal impulse is transmitted on a wireless channel, the received signal appears as a stream of pulses with one pulse for each multiple propagation path. Another characteristic of multipath channels is that each path through the channel can cause the signal to be affected by different attenuation factors. For example, if an ideal impulse is transmitted on a multipath channel, each pulse of the received pulse stream generally has a different signal strength than other received pulses. Another characteristic of a multipath channel is that each path through the channel can cause a different phase in the received signal. For example, if an ideal impulse is transmitted on a multipath channel, each pulse of the received pulse stream generally has a different phase than the other received pulses.

Thus, a wireless channel generally becomes a Time Varying multipath channel due to the relative movement of the structures that create the multipath. For example, if an ideal impulse is transmitted on a time varying multipath channel, the received pulse stream changes in time delay, attenuation, and phase as a function of the time that the ideal impulse is transmitted.

Multipath characteristics of the wireless channel can affect the received signal and, among others, can cause fading of the signal. Fading is the result of the phase-locking characteristics of a multipath channel. Fading occurs when multipath vectors are canceled-synthesized to produce a received signal with a smaller amplitude than either single vector. For example, the first path has a time delay of δ with an attenuation factor of X,, a phase shift of Θrad, and the second path has a time delay of δ with a damping factor of X,, a phase shift of Θ + π rad. When a sine wave is transmitted through a multipath channel having two paths, no signals are received at the output of the channel because two signals of equal amplitude and opposite phase cancel each other. Thus, fading, a type of magnetic interference, or intra-cell interference can have a very negative impact on the performance of a wireless communication system.             

Another characteristic of a cellular communication system is interference from a signal transmitted by other base stations, or a signal transmitted to different sectors of the coverage area of the same base station, causing intercell interference. In general, intercell interference is maximum when the remote station is near the cell boundary, at which first the signal level of the base station is typically minimum and the interference signal from the neighboring base station is maximum.

In-cell and cell inter-cell interference limits the system capacity of the forward link of a wireless communication system. For example, in a communication system based on CDMA, signals from the same base station are separated by a set of orthogonal codes (Walsh codes), where orthogonal codes tend to minimize signal interference of other users in the same base station cell. have. However, first, other signals from the base station still cause magnetic interference or fading. In addition, signals from adjacent base stations are identified by a special short pseudo-random noise (PN) code. All base stations use the same PN code except that the phases are different. However, due to non-zero autocorrelation, cell inter-ference exists.

One way to solve the presented fading problem is to have two separate antennas in the receiver. Separate antennas are structures that generate different or multiple signals. The separate antenna may be separate antennas or may be multiple elements within a single antenna array.

The method of using two separate antennas in a receiver is generally based in part on the idea that both antennas do not simultaneously receive a signal that is undergoing a "deep fade." If the two antennas are completely uncorrelated and there is no usual or complementary relationship to each other, the effect of fading can be reduced by determining the antenna with the maximum signal level and selecting the signal for processing from that antenna. In general, the two antennas are not completely uncorrelated, but typically have low correlation levels, such as envelope correlation below 0.7. The envelope correlation is a commonly used metric for correlation between two antennas. An envelope correlation of 1.0 indicates that the two antennas are completely correlated, producing the same output signal. An envelope correlation of zero indicates that the two antennas are completely uncorrelated and produce output signals from two antennas that have nothing to do with each other.

If the envelope correlation of the two antennas exceeds 0.7, the signals received by both antennas are highly correlated, and the antennas can simultaneously receive signals that experience fading. Thus, highly correlated antennas defeat the efficiency of two-antenna systems in fading, multipath, and communication environments.

The best way to make both antennas uncorrelated is to physically separate them. Separating the two antennas reduces the correlation because the signal paths from the transmitter to each antenna are different. Due to the different signal paths, multipath signals, or multipath vectors, are synthesized differently at each antenna. The multipath vector represents the amplitude and phase of the received multipath signal. Thus, even if multipath vectors are canceled synthesized at one antenna to produce a much smaller, deep faded received signal, the multipath vectors at the other antenna will be different and do not experience fading at the same time.

 When λ is the wavelength of the signal, uncorrelation of the antenna is generally achieved by separating the antennas from each other by at least 0.2λ of the communication signal. For receivers with uncorrelated antennas, several methods are presented for synthesizing the antenna output signal to maximize the strength of the received signal. One method is commonly referred to as Maximal Ratio Combining (MRC), which Joseph C. Liberti, Jr. and Theodore S. Rappaport, described in “Smart Antennas for Wireless Communications: IS-95 and Third Generation CDMA Applications”. In the MRC method, each signal received at the antenna has a magnitude and phase adjusted to a set of weighting terms. Thereafter, the adjusted signals are synthesized. The weight terms are selected to maximize the signal-to-noise ratio (SNR) of the required signal. However, the MRC method does not provide the ability to reject the interfering signal since weighting coefficients are selected to maximize the output of the required signal and at the same time increase the output of the interfering signal.

Another way of synthesizing uncorrelated antenna signals is called Optimal Combining (OC) or “Wiener-Hopf”. In OC, weighting coefficients are determined to maximize signal quality, or the signal-to-interference ratio produced by combining the signals received at the two antennas. Joseph C. Liberti, Jr. See “Smart Antennas for Wireless Communications: IS-95 and Third Generation CDMA Applications,” by Theodore S. Rappaport. The choice of weighting coefficients significantly affects the ability to reject interference.

Methods of synthesizing the received signals on the two antennas have been used with uncorrelated antennas. However, remote station receivers, in particular handsets, are decreasing in size. The reduced size of the receiver makes it difficult to place the antennas at intervals (0.2λ) sufficient to produce an uncorrelated antenna signal.

3 is a block diagram illustrating a typical handset 32, with two highly correlated antenna elements 34 and 35, in accordance with one embodiment. Two antenna elements 34 and 35 are connected to a duplexer 36. The duplexer sends signals from the transmitter circuit 37 to the two antenna elements 34 and 35 or from both antennas to the receiver circuit 38. The transmitter circuit 37 and the receiver circuit 38 interface with the controller 39 and are controlled by the controller 39. Since the elements 34, 35 forming a double antenna are located close together, there is a high correlation between the two antennas 34, 35.

3 shows two antenna elements 34 and 35, the antenna may consist of any desired number of elements. For example, a multi-antenna array may consist of three antennas, four antennas, five antennas, or any other desired number of antennas.

4 is a representative graph showing an interference field of a multipath signal received at each antenna of a multi-antenna array. In FIG. 4, the vertical axis represents signal strength at various positions represented by the horizontal axis. Interference field 40 represents multiple peaks and valleys, or fades, corresponding to the constructive and canceling synthesis regions of each of the multipath signal instances. As shown in FIG. 4, if multiple antennas, for example two antennas, have adequate spacing, there is little chance that both antennas are in a position where the interference field is in a fade state.

For example, in Fig. 4, signal strengths at two different positions are shown for two antennas in an array. At the first position 42, the signal strength 43 at the first antenna is stronger than the signal strength 44 at the second antenna. Thus, signal strength 43 at the first antenna is not fade while signal strength 44 at the second antenna is fade. The difference in signal strength received at the two antennas is due, in part, to the physical separation of the two antennas. If a receiver with two antennas moves in position, the signal level at both antennas will change. For example, if two antennas move to the second position 46, the signal strengths at the first and second antennas correspond to the signal strength 47 and the signal strength 48, respectively. In this example, when the first antenna is in the fade state at the second position 46 and the second antenna is not in the fade state, the receiver moves from the first position 42 to the second position 46 and the two antennas are The relative signal strength of is reversed.

As shown in FIG. 4, physical separation of the antennas in the antenna array contributes to antennas that have different signal strengths and are not correlated. As the spacing between antennas in the antenna array decreases, antenna correlation increases as both antennas receive signal strength closer to the same intensity. In a typical interference field, the minimum distance between peaks and valleys is approximately 0.25λ. In general, a spacing of 0.25λ or more is used between antennas in the antenna array, which results in an envelope correlation of less than about 0.7.

In a multipath environment, antennas of highly correlated antenna arrays are more likely to experience "deep fade" simultaneously. In highly correlated antenna systems, there is a small phase difference between the signals received by each antenna. This allows the multipath vectors received at the antenna to have approximately the same phase relationship. Therefore, the multipath vectors of the received signal will be offset synthesized at one antenna, causing deep fade, and the vector sum of the multipath signal at another antenna will likewise suffer a deep fade.

Also, highly correlated antennas do not have a high “array gain”, the ability to sum the signals received from multiple antenna elements so that the necessary signals are synthesized in phase and coherent without interfering with the interfering signals. . Typical interfering signals include adjacent base station signals, typically referred to as Interferers, received by the antenna. High array gain improves the receiver's ability to reject interfering signals and improves the receiver's ability to operate in a multipath environment. Usually, antennas implemented to have high array gains and high diversity gains require the antenna elements to be uncorrelated. Typically, this requires large spacing between antennas or antenna elements.

In a wireless communication system, using a highly correlated antenna may be beneficial to both remote stations and base stations. In particular, for remote stations, multiple antenna systems will generally be highly correlated. For example, remote stations, such as pocket wireless communication receivers, impose spatial constraints that may make it impossible to have adequate antenna spacing to produce uncorrelated antennas.

Techniques for improving diversity gain and diversity gain of antennas include receiving signals from two antennas. In one embodiment, signals from each of the two antennas are processed by separate receiving circuits. Then, the outputs of the receiving circuit are synthesized.

The complex signal at both antenna outputs contains the amplitude and phase information of the signal. Using the complex signal, an estimation of the complex covariance matrix R is made.

Using the complex signal at the output of the two antenna receivers, the estimation of the complex spatial signature “c” of the desired signal is made. The complex spatial signature of the signal includes the signal amplitude and the angle-of-arrival (AOA) of the signal. In a CDMA based communication system, a RAKE receiver is generally used. In the RAKE receiver, the estimation of the complex spatial signature is performed independently for each signal assigned to the receiver element or finger of the RAKE. For each finger of the RAKE,

ｗ = ((R-Rs) ^-1 )

The weight vector is determined according to Rs, where Rs is a matrix obtained by taking c-Hermitian-Conjugate and c-Outer-Product. Alternatively, ｗ = R ⁻¹ c may produce similar results.

The weight vector is used to adjust the signal received from the antenna before the signal is received by the RAKE receiver. The signal received by each finger of the RAKE receiver is

Ｖ _c (t) = ｗ1 ^* Ｖ1 (t) + ｗ2 ^* Ｖ2 (t)

조절 1 (t) is the complex voltage stream of antenna 1 and Ｖ2 (t) is the complex voltage stream of antenna 2. The weight term ｗ1 ^* is the complex conjugate of the first element of 정의 defined above. The weight term ｗ2 ^* is the complex conjugate of the second element of 정의 defined above.

It has been shown in the test results that the technique can improve the sensitivity of a remote station receiver through both diversity and interference gain in a wireless communication system based on CDMA. In addition, the test results showed that MRC synthesis provided very little gain in the tested situation.             

The technique is used with highly correlated antennas placed very close to each other. The high correlation of the signal is accounted for when estimating the complex covariance matrix R. Thus, although there is only a small difference between the two signals, weighting may be chosen to use this small difference. For example, the weight selected as above is

ｗ1 = 1 + ｚ, ｗ2 = -1 + ｚ or ｗ1 = 1-ｚ, ｗ2 = -1-ｚ

Where ｚ is a small complex number other than zero. The k value is based, in part, on the amount of correlation between the two antennas. For example, two highly correlated antennas may yield a smaller value, while two less correlated antennas may yield a larger value.

For this example, there are two composite voltage streams that can be transmitted to the RAKE receiver. These two voltage streams correspond to two possible sets of weight terms. The corresponding voltage stream is then

BC1 (t) = (Ｖ1 (t)-Ｖ2 (t)) + ｚ ^* (Ｖ1 (t) + Ｖ2 (t))

BC2 (t) = (Ｖ1 (t)-Ｖ2 (t))-ｚ ^* (Ｖ1 (t) + Ｖ2 (t))

Is the same as The correlation between these two voltage streams is very low. To understand how the two highly correlated antenna signals are adjusted and no longer correlated, the following description may be helpful. Since the two antennas are highly correlated, Ｖ1 (t) and Ｖ2 (t) have a strong common mode. The strong common mode between Ｖ1 (t) and Ｖ2 (t) means that both signals will change the level, mostly together. Due to the strong common mode component of the two signals, the difference between the signals, Ｖ1 (t)-Ｖ2 (t), will be small. Ｚ is also a small value. Thus, the sum of the two signals

If you multiply ｚ [ｚ ^* {(1 (t) + (2 (t)}], the result is a small value. The values of ｚ [ｚ ^* {Ｖ1 (t) + Ｖ2 (t)}] and Ｖ1 (t)-Ｖ2 (t) are generally about the same size and are small.

Weighting and synthesizing the two antenna signals results in adding and subtracting voltages of approximately similar magnitude. This technique uses a small difference between the two antenna signals # 1 (t) and # 2 (t). In this way, synthesizing the two antenna signals produces adjusted signals BC1 (t) and BC2 (t) with nearly completely uncorrelated fading characteristics. Also, select the stronger of the two signals to obtain diversity.

FIG. 5 is an exemplary diagram of one embodiment of a highly correlated antenna 50 as may be used for a remote station 52. The embodiment shown in FIG. 5 is a compact “Wand” antenna. The antenna 50 is a dual element antenna and is installed on the remote station 52. Within remote station 52 are two receivers 53 and 54 corresponding to respective elements of antenna 50. The outputs of the receivers are connected to a controller 55 that is adapted to receive multiple antenna inputs. Antenna 50 consists of two planar antennas 56 and 58. The two antennas 56, 58 can be separated, for example, with polystyrene, which is a low dielectric constant spacer.

The two antennas 56 and 58 can separate by about 0.01 to 0.02 wavelengths. In one embodiment, the two antennas 56, 58 separate at 0.05 inches, corresponding to about 0.01 wavelengths at the fabrication frequency.

In another embodiment, the antennas 56, 58 may include, for example, adjacent whip antennas, dual whips with two antennas in a single small plastic strip, dual-fed patches, It may be of different configuration, such as adjacent stubs or whip and coaxial stub antennas.

6 is a block diagram of one embodiment of a dual antenna receiver of a remote station. Each antenna 34 and 35 is connected to a duplexer 60 (connections to the antenna are not shown for simplicity). The duplexer 60 sends signals from the transmitter not shown to the two antennas 34 and 35 and from the antennas 34 and 35 to the receiver circuit. The output of the duplexer 60 is connected to the receiver chain 53. In the receiver chain 53, the output of the duplexer 60 is connected to a low noise amplifier (LNA) 61 in which it is amplified. The output of the low noise amplifier 61 is connected to a mixer 62. The second input to the mixer 62 is a first Local Oscillator (LO). Mixer 62 synthesizes the two signals and outputs an IF signal. The mixer 62 output is connected to a band-pass filter (BPF) 63 which attenuates out-of-band components of the signal. The bandpass filter 63 output is connected to an In-phase / Quadrature (I / Q) Detector 64.

At the I / Q detector 64, the band pass filter output is sent to an In-phase (I) Mixer 65 and a Quadrature (Q) Mixer 66. The second input to the I mixer 65 is a second local oscillator. The second input to the Q mixer 66 is a second local oscillator, phase shifted by 90 °. I and Q mixers 65 and 66 synthesize the output of band pass filter 53 and the second base oscillator signal and the output baseband I and Q components of the received signal, respectively. The I and Q components are sent to Analog to Digital Converters (ADC) 67 and 68 where the signal is digitized. Digital outputs or ADCs 67 and 68 are sent to controller 55 antennas 0 and 1, I and Q, inputs, respectively.

7 is a block diagram of one embodiment of a controller 55 adapted for use as a dual antenna receiver of a remote station. As above, the I and Q components of the two antenna signals become inputs to the controller 55 at each of the antenna (0 and 1) inputs. I and Q signals at antennas 0 and 1 are sent to search engines 70 and 72, respectively. In addition, I and Q signals from both antennas are sent to synthesizer 74. Within the search engines 70 and 72, the antenna signal is evaluated and the spatial signature of the signal received by the finger, as well as the covariance and time delay of the signal carrying the finger are determined as described above and in accordance with known techniques. .

The outputs of the search engines 70 and 72 are connected to a weighting coefficient engine 76 that determines weighting coefficients for each signal received with a finger.

Synthesizer 74 receives weighting coefficients # ₁ and # ₂ from weighting coefficient engine 76. In addition, synthesizer 74 also receives the I and Q components of the two antenna signals. According to one embodiment, synthesizer 74 generally produces one of two possible voltage streams BC1 (t) and BC2 (t). Use a voltage stream with a higher signal-to-noise ratio. These two voltage streams are sent to demodulator 78. Demodulator 78 demodulates two voltage streams.

As used herein, the relationship of “antenna” for “antenna element” and “antenna array” for “antenna” is the same. Both sets of terms have been applied interchangeably throughout the description.

The steps describing a method of implementing various aspects in accordance with the present invention may be performed in a different order without departing from the scope of the present invention. For example, the order in which the steps of the method for processing a multipath signal are performed may be changed without departing from the scope of the present invention.

Information and signals may be represented using any of a variety of other techniques and techniques. For example, data, instructions, commands, information, signals, bits, symbols, chips, etc., which may be referred to in the above descriptions may include voltages, currents, electromagnetic waves, magnetic fields or particles, light fields or particles, Or any combination thereof.

In addition, those skilled in the art will understand that the various illustrated logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented in electrical hardware, computer software, or a combination of both. To clarify this, the interchangeability of hardware and software, various illustrated elements, blocks, modules, circuits, and steps has been described generally in terms of their functionality. Whether such functionality is implemented in hardware or software depends upon the particular application and fabrication restrictions imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure to the scope of the present invention.

The various illustrative logic blocks, modules, and circuits described in connection with the embodiments disclosed herein are general purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware elements, or those designed to perform the functions described herein Can be implemented or performed in any combination of A general purpose processor may be a microprocessor, but in the alternative, may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented in a combination of computing devices, i.e., a combination of a DSP and a microprocessor, a plurality of microprocessors, a microprocessor in conjunction with a DSP core, or any other configuration.             

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed in a processor, or in a combination of the two. The software module may reside in RAM memory, Flash memory, ROM memory, EPROM memory, EEPROM memory, register, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art. have. An exemplary storage medium is coupled to such a processor that can read information from and write information to the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may be present in the user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

The disclosed embodiments have been described above in order that those skilled in the art can make or use the present invention. Those skilled in the art will readily recognize various modifications to these embodiments, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (39)

A multi-element antenna configured to receive signals from one or more transmitters and output a highly correlated signal from each transmitter; Receive the highly correlated signal, determine a complex spatial signature, estimate a complex covariance matrix, including amplitude, arrival angle, and phase for each signal, and transmit a signal from a selected one of the one or more transmitters A controller configured to synthesize the correlated signals to reproduce a; The controller further comprises a weighting coefficient engine configured to determine a set of weighting coefficients for each of the one or more transmitters in response to the complex covariance matrix and the complex spatial signature of the received signal; The weighting coefficient is w = ((R-Rs) ^-1 ) c Wherein w is the weighting coefficient, c is an estimate of the complex spatial signature, R is the complex covariance matrix, and Rs is a matrix formed by taking the c-hermit-conjugate and the cross product of c. Remote station device. The method of claim 1, And the multi-element antenna is a dual element antenna. The method of claim 1, And the multi-element antenna has an envelope correlation greater than about 0.7. The method of claim 1, The controller determines a complex spatial signature of each signal received from the one or more transmitters. The method of claim 1, The controller further comprises a synthesizer configured to synthesize the received signal using the weighting coefficient to reproduce a signal from a selected one of the one or more transmitters. The method of claim 5, wherein And the received signal is synthesized using an optimal synthesizer and the signal to interference ratio is optimized. The method of claim 5, wherein And the received signal is synthesized using a maximum synthesizer and the signal to interference ratio is maximized. The method of claim 1, And the received signal is a CDMA signal. A multi-element antenna configured to receive signals from one or more transmitters and output a highly correlated signal from each transmitter; Receive the highly correlated signal from the multi-element antenna, determine the complex spatial signature, estimate the complex covariance matrix, including amplitude, arrival angle, and phase for each signal, firstly estimate signal amplitude versus other reception. A controller configured to synthesize the correlated signals to maximize the amplitude ratio of the received signal, The controller further comprises a weighting coefficient engine configured to determine a set of weighting coefficients for each of the one or more transmitters in response to the complex covariance matrix and the complex spatial signature of the received signal; The weighting coefficient is w = ((R-Rs) ^-1 ) c Wherein w is the weighting coefficient, c is an estimate of the complex spatial signature, R is the complex covariance matrix, and Rs is a matrix formed by taking the c-hermit-conjugate and the cross product of c. Remote station device. The method of claim 9, And the multi-element antenna has an envelope correlation greater than about 0.7. The method of claim 9, And the multi-element antenna is a dual element antenna. The method of claim 9, The controller further comprises two or more search engines, each search engine configured to receive in-phase and quadrature signals from the antenna element. The method of claim 9, The controller further comprises a synthesizer configured to receive in-phase and quadrature signals from each antenna element, receive weighting coefficients from a weighting coefficient engine, and output an optimized in-phase and quadrature signal. The method of claim 9, The controller further comprising a demodulator configured to receive the optimized in-phase and quadrature signals and to output a demodulated signal. The method of claim 9, And the received signal is a CDMA signal. One or more base stations configured to transmit communication signals; And A remote station configured to receive a communication signal from the one or more base stations with a multi-element antenna, the received communication signal being highly correlated and synthesized to reproduce a signal from a selected base station of the one or more base stations, for each signal One or more remote stations configured to determine a complex spatial signature, including amplitude, arrival angle, and phase, and configured to estimate a complex covariance matrix, The one or more remote stations, including the amplitude, angle of arrival, and phase of each communication signal received from the one or more base stations, determine a complex spatial signature, estimate a complex covariance matrix, and select from one or more transmitters. Further comprising a controller configured to synthesize the correlated signals to reproduce a transmitted signal, The controller further comprises a weighting coefficient engine configured to determine a set of weighting coefficients in response to the complex covariance matrix and the corresponding complex spatial signature for each of the received communication signals; The weighting coefficient is w = ((R-Rs) ^-1 ) c Wherein w is the weighting coefficient, c is an estimate of the complex spatial signature, R is the complex covariance matrix, and Rs is a matrix formed by taking the c-hermit-conjugate and the cross product of c. Wireless communication system. The method of claim 16, And the multi-element antenna is a dual element antenna. The method of claim 16, And the multi-element antenna has an envelope correlation of greater than about 0.7. The method of claim 16, The controller further comprises a synthesizer for synthesizing the received communication signal using the weighting factor to reproduce a signal from a selected one of the one or more transmitters. The method of claim 19, Wherein the communication signal is synthesized using an optimal synthesizer and the signal to interference ratio is optimized. The method of claim 19, And wherein the communication signal is synthesized using a maximum synthesizer and the signal to interference ratio is maximized. The method of claim 16, The communication signal is a CDMA signal. A method of processing a multipath signal, Receiving signals from one or more transmitters at multiple antennas; Estimating a complex covariance matrix; Identifying a preferred transmitter from among the one or more transmitters where the desired signal is received; Generating a signal from each antenna, the signal being highly correlated and comprising a signal component of a desired signal from said first transmitter, and an interference signal; Determining a complex spatial signature, including amplitude, arrival angle, and phase, for each signal; Synthesizing two or more said highly correlated signals to maximize the ratio of said desired signal amplitude to said interfering signal amplitude; Determining a set of weighting coefficients for each received signal in response to the complex covariance matrix and the complex spatial signature of the received signal; And Reproducing a signal corresponding to the desired signal received from the preferential transmitter using the weighting factor, The weighting coefficient is w = ((R-Rs) ^-1 ) c Wherein w is the weighting coefficient, c is an estimate of the complex spatial signature, R is the complex covariance matrix, and Rs is a matrix formed by taking the c-hermit-conjugate and the cross product of c. Multipath signal processing method. The method of claim 23, And the received signal is synthesized using an optimal synthesizer and the signal to interference ratio is optimized. The method of claim 23, And the received signal is synthesized using a maximum synthesizer and the signal to interference ratio is maximized. The method of claim 23, And the received signal is a CDMA signal. A method of processing a signal in a wireless communication system, Receiving signals from a plurality of transmitters with a highly correlated multi-element antenna; Estimating a complex covariance matrix; Determining a complex spatial signature, including amplitude, arrival angle, and phase, of each signal received from the plurality of transmitters; Determining a set of weighting coefficients for each transmitter signal in response to the complex covariance matrix and the complex spatial signature of the received signal; And Synthesizing the received signal using the weighting coefficient to reproduce a signal from a selected one of the plurality of transmitters, The weighting coefficient is w = ((R-Rs) ^-1 ) c Wherein w is the weighting coefficient, c is an estimate of the complex spatial signature, R is the complex covariance matrix, and Rs is a matrix formed by taking the c-hermit-conjugate and the cross product of c. Signal processing method. The method of claim 27, And the multi-element antenna is a dual element antenna. The method of claim 27, And the multi-element antenna has an envelope correlation greater than about 0.7. The method of claim 27, And the received signal is synthesized using an optimal synthesizer and the signal to interference ratio is optimized. The method of claim 27, And the received signal is synthesized using a maximum synthesizer and the signal to interference ratio is maximized. The method of claim 27, And the received signal is a CDMA signal. Means for processing a signal in a wireless communication system, Means for receiving signals from one or more transmitters in multiple antennas; Means for estimating a complex covariance matrix; Means for identifying among the one or more transmitters a preferred transmitter from which a desired signal is received; Means for generating a signal from each antenna, wherein the generated signal is highly correlated and comprises a signal component of a desired signal from the preferred transmitter, and an interference signal; Means for determining a complex space signature, including amplitude, arrival angle, and phase, for each signal; Means for determining a set of weighting coefficients for each received signal in response to the complex covariance matrix and the complex spatial signature of the received signal; And Means for synthesizing two or more said highly correlated signals to maximize the ratio of said desired signal amplitude to said interfering signal amplitude, The weighting coefficient is w = ((R-Rs) ^-1 ) c Wherein w is the weighting coefficient, c is an estimate of the complex spatial signature, R is the complex covariance matrix, and Rs is a matrix formed by taking the c-hermit-conjugate and the cross product of c. Signal processing means. Means for transmitting a communication signal from one or more base stations; Means for receiving a communication signal by one or more remote stations, the remote station being configured to receive a communication signal with a multi-element antenna, the received signal being highly adapted for reproducing a signal from a selected base station of the one or more base stations. Correlated and synthesized communication signal receiving means; Means for estimating a complex covariance matrix; Means for determining a complex space signature, including amplitude, arrival angle, and phase, for each signal; Means for determining a set of weighting coefficients in response to the complex covariance matrix and the complex spatial signature of the received signal, The weighting coefficient is w = ((R-Rs) ^-1 ) c Wherein w is the weighting coefficient, c is an estimate of the complex spatial signature, R is the complex covariance matrix, and Rs is a matrix formed by taking the c-hermit-conjugate and the cross product of c. Wireless communication system. delete delete delete delete delete

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